1. Field of the Invention
The invention relates generally to a flexible platform that generates aerosols and vapors through the volatilization of a liquid for laboratory testing and development of applications for volatilized liquids.
2. Description of Related Art
U.S. Pat. No. 5,743,251, which is incorporated herein by reference, discloses an aerosol generator that includes a tube having a first open end. The aerosol generator further includes a heater for heating the tube to a temperature sufficient to volatilize material in a liquid form in the tube such that the volatilized material expands out of the open end of the tube and mixes with ambient air to form an aerosol.
An aerosol generator 21 according to U.S. Pat. No. 5,743,251 is schematically shown with reference to FIG. 1. The aerosol generator 21 includes a tube 23 having an open end 25. A heater 27 is positioned adjacent to at least a portion of the tube 23, but preferably in a way that provides a heated zone around the tube that maximizes heat transfer evenly throughout the heated zone. The heater 27 is connected to a power supply 29, preferably a DC power supply, such as a battery.
In operation, a material (not shown) in liquid form is introduced to the tube 23. The heater 27 heats the portion of the tube 23 to a sufficient temperature to volatilize the liquid material. In the case of an organic liquid material, the heater preferably heats the liquid material just to the boiling point of the liquid material, and preferably maintains the surface temperature of the tube 23 below 400 C, as most organic materials are not stable when they are exposed to temperatures above that temperature for periods of time. The volatilized material expands out of the open end 25 of the tube 23. The volatilized material mixes with ambient air outside of the tube and condenses to form particles, thereby forming an aerosol.
The tube 23 is a capillary tube or a portion thereof having an inside diameter of between 0.05 and 0.53 millimeter and the inside diameter of the tube can be approximately 0.1 millimeter. The tube 23 can be a portion of a fused silica capillary column, an aluminum silicate ceramic tube, or other substantially non-reactive materials capable of withstanding repeated heating cycles and generated pressures and having suitable heat conduction properties. If desired or necessary, an inside wall of the tube 23 may be provided with a coating for reducing the tendency of material to stick to the wall of the tube, which may result in clogging.
The tube 23 may be closed at a second end 31 and material in liquid form may be introduced into the tube 23 through the open end 25 when it is desired to form an aerosol. Thus, when the liquid material is heated by the heater 27, the volatilized material is only able to expand by exiting the tube 23 through the open end 25. However, the second end 31 of the tube is connected to a source 33 (shown by dotted lines in FIG. 1) of liquid material. The liquid material in the portion of the tube 23 volatilized by the heater 27 is prevented from expanding in the direction of the second end 31 of the tube, and is forced out of the open end 25 of the tube, as a result of back pressure of liquid from the source 33 of liquid material. The back pressure of the liquid is between about 20 to 300psi.
It is contemplated that a variety of uses can be developed for the aerosol generator described above. In order to investigate such uses, it would be desirable to have an instrument capable of generating vapors and aerosols to be evaluated. It would be further desirable to establish operational profiles for controlling the instrument, thereby simplifying the operation of the instrument across a range of operating parameters and conditions.